A marathon runner's staple, energy gels replenish your depleted carbohydrate stores when running.
When you run your body uses two sources of fuel to feed your muscles, fat and carbohydrates. While fat is widely available it’s slower to break down into usable energy making it ineffective when running a marathon.
Instead, your body relies on carbohydrates as its primary fuel source. As a general rule the faster you run, the more your fuel will come from carbohydrates. But your body can only store a limited amount of carbohydrates in our muscles, known as glycogen; at half marathon pace this is about 90 minutes of running and at marathon pace about 120 minutes of running. This means the average runner will be running low on glycogen stores about halfway through their marathon.
This is where energy gels come in. The simple sugars in energy gels are first absorbed into your blood stream as glucose giving you a spike in energy. It’s then absorbed by active muscles and organs. Although energy gels aren’t a direct replacement as you can’t control which muscles the glucose goes to, they do help continue to fuel your run.
Energy gels contain about 25g of carbohydrates per gel, in the form of simple sugars, an accessible energy source for your body to process. One gel provides about 45 minutes of running but taking two at a time doesn’t mean you’ll have 90 minutes of running, instead you’re likely to crash as your body attempts to process the sugar.
They can also contain other ingredients to help boost your performance for example electrolytes to replace lost minerals, and caffine to open up your blood vessels, speeding up the delivery of energy and giving your mind and motivation a little boost too, as well as flavouring. Flavours are often fruits which can be super-food sources like berries that are rich in antioxidants to help clear the muscles of waste products.